It is often necessary in a container manufacturing plant to rotate or turn containers from a vertically aligned position to a horizontally aligned position, or vice versa, in order that the containers may be oriented properly for procedures such as rinsing, coating, and/or printing. One problem associated with conventional rotating devices is that the containers often become jammed as they are rotated resulting in damage to the containers and possible damage to the rotating device.
There are a number of prior art devices for rotating a container. Although these prior art devices may differ in many respects, one thread of continuity running throughout all these prior art devices is that when a system of rods or rails are used to rotate the container, each rod or rail is bent along its length to create the path of movement for the container. Accordingly, the axis of rotation of the container is at the center of mass of the container as it moves to the rotated position.
Typically, many food containers have a cylindrical wall portion and a flanged end cap which attaches to and closes one end of the cylindrical wall portion of the container. The end caps are of greater diameter than the wall portion of the containers. When the containers are in upright side-by-side arrangement, the larger diameter of abutting end caps of adjacent containers creates a space between the cylindrical wall portions of the adjacent containers. During rotation as by the prior art, because there is some amount of clear space between the containers and the rotating device, the containers become slightly misaligned in relation to one another. Accordingly, adjacent end caps tend to ride up on each other and come into contact with the cylindrical wall portion of an adjacent container. This contact causes the adjacent end caps to interfere with each other during rotation. Because most manufacturers desire containers to be processed in a quick and efficient manner, high speed handling of the containers is required. This high speed requirement compounds the problems of jamming and damage to the containers normally encountered even at lower speeds.
Another problem associated with the prior art is that when a container is rotated about its center of mass, the contact between the cylindrical wall portions of the containers as they are rotated results in friction which resists rotation of the containers. Accordingly, a container rotated about its center of mass can result in jamming of the containers due to the undue friction between the containers. Typically, in a container manufacturing plant, the top end of the container is left open to allow whatever product is to be placed in the container at a later time. For both flanged closed end containers and other containers in a manufacturing plant that have a closed bottom end, this bottom end is heavier than the open top end. As a container is rotated about its center of mass such that the heavier bottom end is raised, the lighter top ends of the containers can be compressed against one another such that the top ends become deformed in an elliptical or oblong shape because of the large amount of force required to lift the heavy lower end of the container to rotate it. This deformation can result in jamming and damage to the containers as they are being rotated.
One example of a prior art device that rotates a container along its center of mass is found in U.S. Pat. No. 3,314,522 to Croall. As is typical with the other prior art devices, this reference shows a plurality of rods or rails which all have a curved shape along their length which defines the turning movement of the container along its center of mass. This device incorporates a series of rod-like guides which then communicate with conventional rails once the container has achieved its rotated position.
Other examples of the prior art include U.S. Pat. No. 3,767,028 to Rosso, and U.S. Pat. No. 1,277,782 to Tucker. In these prior art devices, the same manner of rotation is found in which the container is rotated along an axis aligned with the center of mass of the container. These devices incorporate a combination of rods and/or flat surfaced rails which achieve the rotation.
None of these prior art devices provide for tipping a container to a desired position about its lower end which overcome the problems of flanged end-type containers riding up on one another, undue friction between the cylindrical walls of containers, and deformation of the upper end of open containers.